1. Field of the Invention
The present invention relates to a piezoelectric actuator, an inkjet head assembly, and a method of manufacturing the same.
2. Description of the Related Art
In general, an inkjet head is a structure converting electrical energy into physical force to thereby discharge ink in droplet form through a small nozzle. Inkjet heads may be mainly divided into two types, according to the ink discharge scheme. One of the two types is a thermal inkjet head, generating bubbles in ink using a heat source and discharging the ink by the expansive force of the bubbles, while the other thereof is a piezoelectric inkjet head using a piezoelectric substance and discharging ink by pressure applied to the ink due to deformation of the piezoelectric substance.
In particular, the piezoelectric inkjet head has recently been widely used in industrial inkjet printers. For example, the piezoelectric inkjet head is used to spray ink produced by melting a metal such as gold, silver, or the like, onto a flexible printed circuit board (FPCB) to thereby directly form a circuit pattern thereon, or has been used in creating industrial graphics, a liquid crystal display (LCD) or an organic light emitting diode (OLED), a solar cell, and the like.
The piezoelectric inkjet head has a structure in which a piezoelectric actuator is provided on an upper portion of an inkjet head plate including a pressure chamber to thereby apply pressure to ink stored in the pressure chamber. Therefore, an electrode wiring needs to be connected to a driving electrode of the piezoelectric actuator to thereby supply voltage thereto.
However, in general, in the piezoelectric actuator, a liquid piezoelectric substance is applied in paste form, solidified, and then used. Therefore, when a piezoelectric substance is formed to have a shape corresponding to that of the pressure chamber formed to be elongated in a length direction, an upper portion of the piezoelectric substance does not have a flat shape, but is formed to be rounded in a width direction to thereby have an arched shape. Therefore, the driving electrode formed on the upper portion of the piezoelectric substance also has a rounded shape.
Even in the case that the driving electrode has the rounded shape, there may be no problem in the performance of the actuator itself. However, the driving electrode to be connected to a flexible printed circuit in order to receive power may also have a rounded shape, such that it maybe difficult to perform soldering or the like thereon. In addition, even in the case that the driving electrode is connected to the flexible printed circuit, a defect such as short-circuit, or the like, may be generated therein.